Classifications

• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
  • C01G45/00—Compounds of manganese
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
  • C01G45/00—Compounds of manganese
  • C01G45/02—Oxides; Hydroxides
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2006/00—Physical properties of inorganic compounds
  • C01P2006/10—Solid density

Definitions

• the invention relates to an improved method of making manganous carbonate of improved physical properties and of high purity.
• MnCO Manganous carbonate having the chemical formula, MnCO is an important industrial chemical. Among its uses is that of making Mn0 which may be accomplished by merely heating the MnCO in the presence of excess oxygen gas, e.g., air.
• MnO manganese dioxide
• dry cells wherein the electrolyte consists of an aqueous paste of an electrolytic salt, e.g., NH4C1, and a depolarizer intermixed therewith, the preferred material therefor being MHO2.
• an electrolytic salt e.g., NH4C1
• depolarizer intermixed therewith, the preferred material therefor being MHO2.
• MnCO has a bulk density usually not greater than about 10 grams (and frequently lower) per cubic inch. It is desirable that MnCO have a bulk density of .at least about 15 grams and preferably atleast about 20 grams per cubic inch. (It is customary in the trade to state the density of this type of product in grams per cubic inch, i.e., metric weight units per English volume unit.)
• the principal object of the invention is to provide a method of making MnCO having the above designated desired density.
• the manner of carrying out the invention to attain this and related objects is made clear in the ensuing description and is succinctly defined in the appended claims.
• the invention accordingly, in a broad sense, is the method of preparing high density MnCO by an improved and heretofore unknown process which comprises admixing aqueous solutions of a water-soluble manganous salt with a water-soluble carbonate in relative proportions of each to provide and maintain a molar excess of the Mn fraction of the manganous salt over the CO fraction of the soluble carbonate therein, at a pH value of between about 5.7 and about 7.2, under stirred conditions, at a temperature of between about 55 C.
• MnCO in suspension to make a slurry; maintaining the MnCO in suspension until the particle size and the concentration of the suspended MnCO in the slurry are such as to insure a bulk density of the MnCO of at least 15 grams per cubic inch, and preferably at least about 20 grams per cubic inch; and separating the MnCO so produced.
• the bulk density of the MnCO product may be determined by one of several procedures, two of which are set out in detail hereinafter.
• the conditions requiring a molar excess of Mn over CO i.e., a molar ratio of Mn to CO of more than 1, and the specified temperature requiring a temperature not lower than about 55 C. are critical. When these conditions are not observed, there is an objectionable amount of Na CO and/0r NaHCO occluded in the MnCO product.
• the pH limits must also be observed. Since Na CO raises the pH and MnCl lowers it, the pH is easily adjusted by regulating the flow of feed within the "Ice required molar ratio.
• the period required for obtaining proper density MnCO is at least about 1.5 hours; usually 3 to 5 hours are employed.
• Thev concentration of the aqueous feed solutions are not critical. However, it is recommended that the concentration be at least about 5% by weight and preferably that it approach the saturation point of the solutions at the temperature employed.
• a preferred mode of practicing the invention is to admit metered flows of aqueous solutions of Na CO and MnCl of a concentration of say at least about 10% by weight, into a stirred reactor, at a rate to provide more than 1 but not appreciably over about 1.05 moles of Mn per mole of CO groups, at .a reactor temperature of between about C. and about C.
• One satisfactory procedure for ascertaining the bulk density of the MnCO being produced is as follows: 1000 milliliters of the aqueous MnCO slurry, from the reaction mixture, is put in a 1000-milliliter graduate and allowed to stand therein undisturbed for seven minutes. During this time, the MnCO therein settles to the bottom forming (with a small amount of entrapped NaCl-containing mother liquor) the lower of two distinct layers, the upper layer being the major portion of the mother liquor.
• the volume of the low layer, comprising the MnCO and the entrapped mother liquor is then recorded in milliliters and the weight of MnCO in the lower layer ascertained by decanting oif substantially all the upper layer, filtering, washing, and drying the MnCO in the lower layer, and weighing the resulting dried filter cake.
• the actual weight of MnCO thus obtained is both the amount in grams, the lower layer, and the density of the slurry in the reaction vessel in grams per liter.
• the ratio of the density of the body of stirred sus pension in the reaction vessel in grams per liter to the volume of the MnCO and entrapped mother liquor making up the lower layer of the Stratified 1000-milliliter sample is then ascertained and is converted to grams per cubic inch by multiplying the density in grams per cubic centimeter by 16.4, the value of (2.54) since 1 inch equals about 2.54 centimeters.
• the resulting answer is substantially the density of the MnCO in grams per cubic inch. For example, if the weight of MnCO in the lower layer is 60 grams (which is also the density in grams per liter) and the volume of the lower layer of MnOO and entrapped mother liquor is 80 milliliters, then the above procedure may be expressed:
• the density of the MnCO is about 12 grams per cubic inch.
• W is the. total weightof MnCO and mother liquor in the 1000-milliliter sample
• 1- is the crystal density of MnCOg
• 'X is the true volume occupied by MnCO in milliliters (not the apparent or, visually measurable volume) in the 1'000-millilite-r'sample
• p2 is the density of and X can be expressed as pl p2 the true volume of MnCOg.
• Thebulk density is found by the equation:
• the density in grams per cm. can be converted to grams per in. by multiplying it by
• the feed rates and agitation are thereafter held substantially constant and the upper part of the slurry in the reaction vessel caused to overflow, in a continuous manner, into areceiving trough or conduit which preferably carries it to a settling tank.
• a substantial portion of the mother liquor is removed, usually continuously, from the upper part of the settling tank and the wet slurry from the lower part from which it is conveyed to a filter.
• the MnCO is washed, removed from the filter, and thereafter dried and (as desired) stored or used.
• Example 1 The vessel employed was a 60-gallon glass lined kettle provided with an anchor-type agitator and a recycle pump and. return line (which provided circulation, from the bottom to the top of the kettle). An enclosing jacket was connected to hot .and cold water sources for heating and cooling, as needed- A pH'meter was positioned in the recycle line so that the pH value could be ascertained at any time.
• the kettle was provided with two metered feed line sand an overflow line which were equipped with suitable flow control means.
• the recycle line was provided with a means for obtaining samples of the reaction mixture.
• a settling test of the slurry was taken and the density of the MnCO therein found to be 12.2 grams per cubic inch. At that time, about 30 gallons of the slurry were removed from the kettle, filtered, and the MnCO on the filter returned to the kettle to build up the solids. After 3.15 hours from the start-up, a second settling test was run on the slurry and the density of the MnCO therein found to be 25 grams per cubic inch. The slurry so removed was, as above, filtered, and the MnCO collected in thefilter and returned to the kettle to build up further the solids.
• a third settling test was run and the density of the MnCO found to be 27 grams per cubic inch. At that time, another 30 gallons of the slurry were removed from the kettle, the MnCO separated by filtration and returned to the kettle to continue to build up the solids. After a total time of 5.25 hours from the start-up, another settling test was run which showed the density of the MnCO to be 23.0 grams per cubic inch. Provision was then made for overflow from the kettle at the rate of about 29 gallons per hour. The overflow was continuously filtered and the MnCO therefrom retained, washed, and dried. A settling test was run after 9.15 hours (total operating time) and showed the MnCO to have a density of 26 grams per cubic inch.
• the run was continued for a total time of 30.1 hours during which 490 pounds of MnCO having an average density of 24.5 grams per cubic inch, were made.
• MnCO was produced in suspension at the rate of 1.075 moles per minute. This was 123.5 grams per minute, which was 67.4 grams per liter of reaction mixture. NaCl was produced in solution at the rate of 2.15 gram moles per minute. This was 125.8 grams per minute or 68.6 grams per liter. A total of 2.3 grams or 1.28 grams per liter of the. Mn portion of the MnCl remained unreacted. This represents an efficiency, in the yield of MnCO based on the weight of MnCl of 98.0%.
• the pH value was controlled throughout the run at between 6.0 and 6.2.
• the temperature was controlled throughout the run atbe: tween C. and C.
• the MnCO so made was tested for the following alkaline materials which were found to be present as follows: NaHCO trace; NaOH and Na CO none. A trace of NaCl was found. It was also analyzed for the impurities normally associated therewith when made by conventional processes, which :were found in thearnounts stated in Table I below:
• MnCO made according to Example 1 was employed to make MnO by heating the MnCO in air to form a dense, free-flowing MnO powder. This air-oxidized product was then contacted with dilute sulfuric acid and heated to leach out any unconverted MnCO and lower oxides of manganese. The leached product was washed, dried and used to form the cathode mix of a Leclanch For purposes of comparison the following test run was A cell battery according to standard formulation.
• the bulk 115mg M1102 P p from 8 60111111011 eommerelal 10W d i was 153 grams Per bi i h bulk denslty MnCO for comparative purposes.
• the re- 690 grams of the product so made were admixed with suits are shown in Table II.
• Example 4 shows a significant advantage of employing stirring, to 59 C.
• the pH value (which was 8.6 after high density, high purity MnCO according to the invenheating) was adjusted by additional MnCl solution to tion to make MnO for dry cells over currently available 6.35.
• the mixture was then cooled to room temperature MnO (made from MnCO made according to convenand the MnCO product, separated, washed, and dried. tional practice).
• the method of making high density MnCO of high which comprises admixing an aqueous solution of invention, grows dentritically, to a desirably high dena water-soluble manganous salt with a water-soluble carsity material of relatively low surface area and high bonate in amounts of each to provide and maintain a molar percent Mn, the latter indicating its purity.
• the MnCO excess of the Mn fraction of the manganous salt over the of the invention has a surface area of less than 5 square CO fraction of the carbonate at a pH value of between meters per gram and a Mn content of at least 44% after 5.7 and 7.2, under stirred conditions, at a temperature of drying at 110 C.
• the MnCO made according to Exbetween about 55 C. and the boiling temperature of the ample 1 had a surface area of less than 0.3 square meter admixture to produce MnCO in suspension to make a per gram as determined by the standard B.E.T. method slurry; maintaining the MnCO in suspension until the employing the liquid nitrogen absorption principle. It particle size and concentration of the suspended MnCO was 44.4% after drying at 110 C. in slurry are such as to insure a bulk density of the MnCO of at least 15 grams per cubic inch; and separating the Example 2 MnCO so made.
• Example 1 The procedure of Example 1 above was repeated eX- eept that the temperature was maintained at between perature of the reaction mixture is maintained between 52' C. and 61 C., the pH value was held at between about ahd about 6.8 and 6.9, and the run was continued (being stirred
• the method aeeofdlng 6121111 1 Wh reln the molar and recycled) for only 50 minutes before the MnCO 6O ratio of P to CO3 PV by h mahgaheus Salt and being f d Showed a total alkalinity, Calculated as carbonate in the reaction mixture is more than 1 but not NaHCO to be 0.2, and portions of the slurry were not more than about drawn off, filtered, and the MnCO on the filter returned m h aeofdihg to Claim 1 WheIeih the P to the reaction vessel. This is' :barely acceptable and Value 15 malhtalhed between about and about 6.9.

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Inorganic Chemistry (AREA)
• Inorganic Compounds Of Heavy Metals (AREA)
• Compounds Of Alkaline-Earth Elements, Aluminum Or Rare-Earth Metals (AREA)

Priority Applications (7)

Applications Claiming Priority (1)

Publications (1)

Family

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Family Applications (1)

Country Status (7)

Cited By (3)

Citations (2)

• 1963
  • 1963-06-12 US US287192A patent/US3262752A/en not_active Expired - Lifetime
• 1964
  • 1964-05-26 GB GB21677/64A patent/GB1028397A/en not_active Expired
  • 1964-06-08 FR FR977386A patent/FR1397864A/fr not_active Expired
  • 1964-06-08 LU LU46271D patent/LU46271A1/xx unknown
  • 1964-06-09 DE DED44632A patent/DE1242584B/de active Pending
  • 1964-06-12 BE BE649228A patent/BE649228A/xx unknown
  • 1964-06-12 NL NL6406674A patent/NL6406674A/xx unknown

Patent Citations (2)

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